[lldb] Improve CPUInfo test predicate

Use a with block for reading the cpuinfo file.

When loading the file fails (or we're not on Linux)
return an empty string. Since all the callers are
going to do "x in self.getCPUInfo()".

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D99729

Author: DavidSpickett

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -1274,7 +1274,7 @@ def getCPUInfo(self):
 
         # TODO other platforms, please implement this function
         if not re.match(".*-.*-linux", triple):
-            return False
+            return ""
 
         # Need to do something different for non-Linux/Android targets
         cpuinfo_path = self.getBuildArtifact("cpuinfo")
@@ -1284,11 +1284,10 @@ def getCPUInfo(self):
             cpuinfo_path = "/proc/cpuinfo"
 
         try:
-            f = open(cpuinfo_path, 'r')
-            cpuinfo = f.read()
-            f.close()
+            with open(cpuinfo_path, 'r') as f:
+                cpuinfo = f.read()
         except:
-            return False
+            return ""
 
         return cpuinfo